I’ve done solder paste freehand at an internship- this was the standard method for single-part attachment for testing. We had syringes full of solder paste with fine-diameter needles, and a compressed-air system regulated by a pedal to activate the flow. This took very steady hands (and a giant microscope). With a great deal of practice I got down to parts with six pads in 0.9mm2 (about 0.12mm2 per pad)
Tl;dr - it is possible, but slow and difficult

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